Previous systems for the agitation of manure stored in an open top tank utilized a single center agitation nozzle as in Kellogg U.S. Pat. No. 3,367,583 which was operated from the top and spaced from the floor of the tank. The nature of manure storage depends on successful mixing and blending of solids and fibers with the liquid in the manure into a homogenized mass which can easily be handled with pumps and field spreading equipment. Also a system to break the crust in the upper portions of the stored manure slurry is required. The present invention provides an emergency system whereby manure may be withdrawn from the storage tank and circulated into the top of the crust to break it up or the manure may be discharged into a spreader.